This research proposal is designed to provide information of the regulation of growth hormone and prolactin secretion by normal human beings and by patients with pituitary tumors. We will attempt to detect hypophysiotropic hormones regulating GH and Prl by extracting peptides from peripheral blood, followed by desalting and concentration. The hypophysiotropic hormones will be quantitated by radioimmunoassays when available by quantitative bioassay using primary culture of bovine pituitary cells. We will determine the responsiveness of normal human pituitary cells and cells from GH and Prl secreting pituitary adenomas to hypophysiotropic hormones in primary cell or organ cultures. We will continue our studies of the possible control of GH and Prl secretion of pituitary tumors with drugs acting on adrenergic and dopaminergic receptors. We will use radioreceptor assays of GH in an attempt to detect abnormal forms of growth hormone which might be responsible for impaired growth. We will investigate hormonal and metabolic factors which influence the concentration of GH and Prl receptors in liver, mammary gland.